Rainfall

Statewide annual average rainfall for 2009 was 484.0 mm. This is below the normal of 559.0 mm. An El Niño event contributed to the dry conditions experienced in the second half of the year.

Most inland areas and the southern half of the NSW coast recorded below average rainfall. In contrast, the Mid North Coast recorded well above average falls for the year, with Coffs Harbour in particular flooding five times this year.

The rainfall pattern as shown in the rainfall decile map for 2009 reflects the common rainfall pattern experienced throughout the year. Areas in southwest NSW generally experienced below average falls throughout 2009 with the Mid North Coast recording above average falls in February, April, May, June, October and November which corresponds to the 5 floods in Coffs Harbour this year. August was the driest month with all of NSW recording below average rainfall whilst June was the wettest for inland areas.

The Murray Darling Basin recorded a basin wide average of 400.0 mm which is below the historical average1 of 493.4 mm. The past decade is now the driest on record for the Murray Darling Basin.

Temperature

2009 was the warmest year on record for the state of NSW. Very high temperatures experienced throughout the second half of 2009 are likely due to the influence of the 2009 El Niño combined with the background, long-term warming that has been observed across Australia since the start of last century. The mean temperature anomaly for the year was +1.32°C above the 1961-1990 average well ahead of the previous record of +1.13°C set in 2007. Every year in the last decade has been warmer than average, and four of the five warmest years on record for NSW have now occurred since 2002.

The generally warm conditions were exacerbated by three extreme heat events in 2009; a heatwave at the end of January/early February in southwest NSW, extreme heat during August in northern NSW and an exceptional heatwave - both in strength and duration - in November across all of NSW (for more information please see phenomena section below). These extremely warm conditions also contributed to NSW recording the warmest winter and warmest spring on record.

Maximum Temperature

The statewide average maximum temperature for 2009 was 25.4°C which is 1.5°C above the 1961-1990 normal. Eleven months recorded above average maximum temperatures; only April with an anomaly of only -0.03°C was cooler than average.

Minimum Temperaure

Minimum temperatures were also above average with NSW recording an average of 11.9°C which is 1.2°C above the historical average of 10.7°C. Nine out of the twelve months recorded above average minimum temperatures with November being the stand out month with an anomaly of +4.61°C.

Other phenomena

Extreme heat

A slow moving high pressure system in the Tasman produced a heatwave over much of south eastern Australia, including the southern part of NSW towards the end of January continuing into early February. This resulted in several locations breaking records for heatwave duration. For more information please see the Bureau's Special Climate Statement issued 4th February 2009.

Exceptional heat between the 23rd to 25th of August resulted in many records in northern parts of NSW being broken by several degrees. Mungindi recorded the highest temperature of 37.8°C which is the highest temperature recorded anywhere in NSW during winter. The highest record breaking margin was in Murwillumbah where the previous record of 30.8°C was broken by 5.1°C on the 24th of August. Other locations also broke their all time records including Moree, Byron Bay and Lismore. For more information please see the Bureau's Special Climate Statement issued 26th August 2009.

Daily maximum and minimum temperature records were broken during the November heatwave (between the 7th and 22nd) which also set new records for the spring statewide daily maximum and minimum temperature: 46.8°C at Wanaaring PO on 20th November and 33.3°C recorded at White Cliffs Airport on the 19th. For more information please see the Bureau's Special Climate Statement issued 24th November 2009.

Dust storms

NSW experienced two large and extensive dust storms. The more extreme occurred on the 23rd of September resulting in reduced visibility at many locations. On the morning of the 23rd visibility in Sydney was reduced to 400 metres over much of the city. A thick layer of red dust coated all exposed surfaces with many flights delayed or cancelled at Sydney Airport. The dust originated from South Australia and western NSW, and traversed across the state affecting areas as far north as Cairns. A few days later, strong winds again caused raised dust on the 25th reducing visibility to 800 m at 3 pm at Broken Hill, with the dust extending to Sydney by the morning of the 26th. More dust storms of lesser extent occured in October.

Floods

Flooding on the north coast occured five times during summer, autumn and spring 2009. Major rainfall produced by an East Coast Low (ECL) between 13th - 17th of February caused major flooding on the Mid North Coast, including Maitland and Bellingen. This was followed by very heavy falls at the start of April, causing major flooding at many locations within the Mid North Coast and Northern Rivers districts. Between the 19th and 23rd of May heavy falls (although comparatively lower than those in April) preceded by persistent wet conditions, caused flooding on the north coast, affecting Grafton and Kempsey. On the 27th October Coffs Harbour flooded for the fourth time and with little time to recover more rainfall caused flooding in Coffs Harbour between the 6th and 9th of November.

The year ended with the passage of a decaying tropical cyclone from northwestern Australia. Many northern inland areas experienced flooding due to the widespread rain which fell late on Christmas Day and continued through till the end of 2009.

Notes

A Annual Climate Summary is prepared to list the main features of the weather in New South Wales using the most timely and accurate information available on the date of publication; it will generally not be updated. Later information, including data that has had greater opportunity for quality control, will be presented in the Monthly Weather Review, usually published in the fourth week of the month.

This statement has been prepared based on information available at
10 am on Monday 4 January 2010.
Some checks have been made on the data, but it is possible that results will change
as new information becomes available.

A note about deciles: Deciles are used to give an element (in this case rainfall or temperature) a ranking. Deciles are calculated by arranging the totals in ascending order (from lowest to highest) then splitting them into 10 equal groups (thus the groups are called deciles). The first group would be in decile range one, the second group in decile range two, etc up to the highest annual totals (highest 10 per cent) being in decile range 10.

1Averages: Averages are based on the period 1961 to 1990 which is a convention of the World Meteorological Organisation

Normals are long-term averages based on observations from all available years of record, which vary widely from site to site. They are not shown for sites with less than 20 years of record for temperature and less than 30 years of record for rainfall, as they cannot then be calculated reliably.